The deal is for $54 million and could be worth up to $66.5 million with incentives, a source told ESPN's Adam Schefter. The deal also includes $26.5 million in guaranteed money, according to the source.
Bortles was due to make $19.053 million in 2018 after the team picked up his fifth-year option in May.
"I told Ryan [Tollner], my agent, let's just get it done so I can just go play football. I really would love to just know and have confirmation that this is where I'm going to be, and now let's go work and continue to build on what we did last year and go play," Bortles said. "So, happy and relieved. Obviously extremely excited. It's a dream come true to be able to sign a second contract by the team that drafted me. That was one of my goals from the start, so excited to get it all done and get rolling now."
Bortles had a rough start to 2017 -- after a five-interception practice in training camp, coach Doug Marrone opened up the quarterback competition during the preseason -- but he rebounded and put together the best year of his career. Bortles completed 60.2 percent of his passes (the first time he surpassed the 60 percent mark) for 3,687 yards and 21 touchdowns with 13 interceptions.
"I've been around Blake for the past three seasons, only one as the head coach, but I have seen him grow considerably in all facets: the way he prepares, the way he takes care of his body, the way he leads the team, the way he holds himself and his teammates accountable," Marrone said. "I have said it all along -- I think Blake is one of the toughest people I have ever met, and I'm talking about his mental and physical toughness. He never lets the outside noise get him away from where his focus is, which is always on being a great teammate and being a great leader for our organization."
Jacksonville went 10-6, won the AFC South -- the franchise's first division title since 1999 -- and made the playoffs for the first time since the 2007 season. The Jaguars beat the Buffalo Bills at home and Pittsburgh Steelers on the road to reach the AFC Championship Game against New England at Gillette Stadium.
The Jaguars held a 10-point fourth-quarter lead before the Patriots rallied for a 24-20 victory.
Bortles completed 58 percent of his passes for 594 yards and three touchdowns with zero interceptions in the postseason. He also ran 17 times for 121 yards, including 88 yards in the victory over Buffalo. He led a pair of fourth-quarter touchdown drives to help the Jaguars beat the Steelers 45-42.
He didn't exactly have a full complement of receivers either. Allen Robinson suffered a torn left ACL on the third play of the season, and veterans Allen Hurns and Marqise Lee combined to miss eight games. Undrafted rookie Keelan Cole and fourth-round pick Dede Westbrook, who missed the first nine games of the season recovering from sports hernia surgery, were Bortles' main options during a late-season stretch.
"Blake's growth and development last season was a key to the success we had as a team," said Tom Coughlin, the Jaguars' executive vice president of football operations. "Blake has proven, with toughness and dependability, that he can be the leader this team needs going forward. Along with this contract come high expectations that he will continue to improve and help our team accomplish its ultimate goal."
The Jaguars drafted Bortles third overall in 2014. After a rough rookie year, he seemed to have a breakout season in 2015, when he set single-season franchise records in passing yards (4,428) and passing touchdowns (35).
However, he also threw 18 interceptions that season. The former UCF standout led the NFL in turnovers from 2014 to 2016 (63), and his 51 interceptions during that span were second only to Philip Rivers' 52.
Bortles regressed in 2016, and Coughlin, who was hired in January 2017, put him on notice to cut down on turnovers. Bortles averaged 21 turnovers in each of his first three seasons but turned the ball over 16 times in 2017, including an interception that was ripped away from tight end James O'Shaughnessy.
The quarterback has completed 59.1 percent of his passes for 14,928 yards and 90 touchdowns with 64 interceptions in four seasons with the Jaguars. He has run for 1,410 yards and seven touchdowns and is 21-40 as a starter.
Bortles ranks second in franchise history in touchdown passes and interceptions and third in passing yards, attempts and completions.